Barbara Gerbasi longed to study ballet when she was young, but her dreams of donning a tutu and pink satin shoes were at odds with her mother, who preferred she learn piano. It wasn’t until she turned 16 that she enrolled in ballet, paying for classes with baby-sitting money.By the time she was married with children, there was little time for recreation. Shortly after she turned 60, though, she saw an ad in a local newspaper for ballet classes and decided to pick up where she left off. “I went to a ballet class during my lunch break at work,” recalls Gerbasi, who lives in Manhasset. “I was embarrassed, so I wasn’t going to tell my secretary — but then I thought, ‘What if something should happen to me? Someone should know where I am and what I’m doing.’ “A couple of weeks later, she summoned the nerve to tell her husband she had signed up for lessons. “He thought I was crazy and told me I was too old for ballet,” says the grandmother of six. “Friends said, ‘You’re going to do what?’ “That was 16 years ago. Gerbasi, now 76, is still dancing. “I am fulfilling my dream and doing what I always wanted to do,” says the retired public relations consultant and freelance writer Gerbasi and other older adults are taking their places along the ballet barre and living out their childhood fantasies. Once the province of the young, ballet is drawing late-life ballerinas and, to a lesser extent, male ballet dancers, who are returning to the art after a decades-long absence. Some, with no previous experiences, are attempting pliés and pirouettes for the first time.There is no statistical data on how many in the over-50 set are skipping yoga or the gym for ballet, but experts say the physically strenuous and mentally challenging pastime can improve vitality and provide a social outlet for older adults.Ballet is low-impact, aerobic, weight-bearing, great core training and great for joint mobility, because you work the muscle in numerous positions,” says Chris Freytag, an emeritus member of the board of directors of the San Diego-based American Council on Exercise. “And it’s great for brain fitness, because you have to connect your brain to doing a number of steps or sequences.